1) A passive attack is a network attack in which a system is monitored and sometimes scanned for open ports and vulnerabilities. The purpose is solely to gain information about the target and no data is changed on the target.Passive attacks have to do with eavesdropping on, or monitoring, transmissions. Electronic mail, file transfers, and client/server exchanges are examples of transmissions that can be monitored. Passive threat are very difficult to detect and equally difficult to prevent as well, where as active threats continue to make a changes to the system, they are easy to find out & fix as well.Malicious misuse/malicious intent is any from of tampering of the computer system which includes penetration or any form of illegal attraction of the computer which also includes the generation of illegal codes to alter the standard codes within the system.
An active attack is a network exploit in which a hacker attempts to make changes to data on the target or data en route to the target. Types of active attacks: In a masquerade attack, the intruder pretends to be a particular user of a system to gain access or to gain greater privileges than they are authorized for.Sabotage ,Accident Errors and Espionage Agents are all active threats.
2) Varray stands for variable-size array. Varray can be stored in the columns of your tables. When you create varrays you must provide the maximum size for them. They retain their ordering and subscripts when stored in and retrieved from a database table. They are similar to PL/SQL table, and each element in a varray is assigned a subscript/index starting with 1.These are dense and Not sparse, which means there is no way to delete individual elements of a Varray.
3)The data dictionary is full of 'Metadata', information about what is going-on inside your database.The data dictionary is created when the Oracle database is created. It is owned by the SYS user, and is stored principally in the SYSTEM tablespace, though some components are stored in the SYSAUX tablespace in Oracle Database 10g. The data dictionary is comprised of a number of tables and Oracle views.No Oracle user should ever alter (
INSERT) any rows or schema objects contained in the
SYSschema, because such activity can compromise data integrity. The security administrator must keep strict control of this central account.
4)Spanning Tree Protocol (STP) is a Layer 2 protocol that runs on bridges and switches. The specification for STP is IEEE 802.1D. The main purpose of STP is to ensure that you do not create loops when you have redundant paths in your network. Loops are deadly to a network.
- Roll back transactions when a
ROLLBACKstatement is issued
- Recover the database
- Provide read consistency
- Analyze data as of an earlier point in time by using Oracle Flashback Query
- Recover from logical corruptions using Oracle Flashback features.
6) The BIOS (Basic Input/Output System and also known as the System BIOS, ROM BIOS or PC BIOS) is a type of firmware used to perform hardware initialization during the booting process (power-on startup) on IBM PC compatible computers, and to provide run time services for operating systems and programs.The BIOS firmware is built into personal computers (PCs), and it is the first software they run when powered on.
7) RSA is one of the first practical public-key cryptosystems and is widely used for secure data transmission. In such a cryptosystem, the encryption key is public and differs from the decryption key which is kept secret. In RSA, this asymmetry is based on the practical difficulty of factoring the product of two large prime numbers, thefactoring problem. RSA is made of the initial letters of the surnames of Ron Rivest, Adi Shamir, and Leonard Adleman, who first publicly described the algorithm in 1977. RSA is a relatively slow algorithm, and because of this it is less commonly used to directly encrypt user data. More often, RSA passes encrypted shared keys for symmetric key cryptography which in turn can perform bulk encryption-decryption operations at much higher speed.
8) INITRANS is a block level storage parameter which can be specified while creating a object (). INITRANS and MAXTRANS parameters are used to control the concurrent access to the same block. There can be a maximum of 255 concurrent sessions that can access a block at any given time. So the maximum value for MAXTRANS parameter is 255. The value specified through INITRANS are taken into consideration for creating the initial number of ITLs (Intersted Transaction Entries) in the block.While creating the table if INITRANS 20 is specified, then 20 different ITL slots will be created in the block transaction variable header.
Each and every ITL entry in the block transaction variable header takes 24 bytes. Though a block can have a maximum of 255 different ITLs , the block is quite limited to allocate only some defined ITLs in the header. The database block size plays a important role in allocating the number of inital ITLs for the blocks.